A new local composition model, Segmental-Wilson Non-Random Factor (S-Wilson-NRF), based on volume fraction is developed. The new activity coefficient model consists of combinatorial and residual terms that the combinatorial Flory-Huggins equation and the S-Wilson-NRF function are used for the entropy and enthalpy terms, respectively. This model for non-polymeric systems reduces to Nonelectrolyte-Wilson-NRF model. The present model with two dependent adjustable energy parameters is applied to correlation of the activity of solvent for 24 binary polymer systems at various number-average molar masses of polymer and temperatures. Moreover, the results of the present model are compared with the other local composition models such as Nonrandom Two-Liquid (NRTL), NRTL-Nonrandom Factor (NRTL-NRF) models and the Flory-Hugginsmodel. Finally, the new model is applied for correlation of the excess molar enthalpy of the binary polymer solutions at the different conditions. As a conclusion, the results of the new model are in good agreement with the experiment.